CN1076920C - Remotely actuated switch and protection circuit - Google Patents

Remotely actuated switch and protection circuit Download PDF

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Publication number
CN1076920C
CN1076920C CN93109522A CN93109522A CN1076920C CN 1076920 C CN1076920 C CN 1076920C CN 93109522 A CN93109522 A CN 93109522A CN 93109522 A CN93109522 A CN 93109522A CN 1076920 C CN1076920 C CN 1076920C
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circuit
voltage
switching
line
current
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Expired - Fee Related
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CN93109522A
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CN1085701A (en
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D·M·普赖亚
M·查里斯
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Raychem Ltd
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Raychem Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H02H3/10—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current additionally responsive to some other abnormal electrical conditions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M3/00—Automatic or semi-automatic exchanges
    • H04M3/18—Automatic or semi-automatic exchanges with means for reducing interference or noise; with means for reducing effects due to line faults with means for protecting lines
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M3/00—Automatic or semi-automatic exchanges
    • H04M3/22—Arrangements for supervision, monitoring or testing
    • H04M3/26—Arrangements for supervision, monitoring or testing with means for applying test signals or for measuring
    • H04M3/28—Automatic routine testing ; Fault testing; Installation testing; Test methods, test equipment or test arrangements therefor
    • H04M3/30—Automatic routine testing ; Fault testing; Installation testing; Test methods, test equipment or test arrangements therefor for subscriber's lines, for the local loop
    • H04M3/301—Circuit arrangements at the subscriber's side of the line
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
    • H02H9/041—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage using a short-circuiting device

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Monitoring And Testing Of Exchanges (AREA)
  • Selective Calling Equipment (AREA)
  • Electrophonic Musical Instruments (AREA)
  • Emergency Protection Circuit Devices (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Electronic Switches (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Monitoring And Testing Of Transmission In General (AREA)
  • Devices For Supply Of Signal Current (AREA)

Abstract

A switching arrangement that can be connected in a communications channel comprising a pair of lines, between sets of terminal equipment, which comprises: (i) a pair of series switching circuits, each of which can be series connected in one of the lines and will open when subjected to an overcurrent in its associated line; and/or (ii) one or more shunt switching circuits connected between the lines, or between one or both the lines and earth, and will close when subjected to an overvoltage in its associated line; wherein the or each switching circuit can be remotely actuated by means of a test signal sent along the channel.

Description

Remotely actuated switch and protective circuit
The present invention relates to communicating circuit, the maintenance terminal unit that particularly in telephone circuit, uses.
In recent years, especially consider to dwindle country to the dried scope of giving of economy in many telephone systems, for this system, the private more and more communication apparatus of oneself of having installed in the user, its result often is necessary to determine that arbitrary fault is to be on the telephone wire, or in user family, promptly be necessary to determine whom is responsible for repairing this fault by, if thisly determine by just finishing along the line from this local switch long distance one proper signal to user family, this is quite high on economic benefit, therefore, just avoided sending any necessity of making a phone call to carry out the personal contact to the user.
At first be necessary to install a kind of what is called " maintenance terminal unit or the MTU on the line of user family; this user can be immediately disconnects (this line claims segmented line usually) with subscriber equipment from this line; and connect a and b or end line, and loop wire is received the appropriate signals of coming from switch in order to detect the telephone wire that is used for any fault.During this line testing process, thisly will typically constitute by line-line resistance and this first and second lines resistance to earth to the definite of fault.And the continuity of this line can detect the way that MTU exists with method for electrically and determines.
The various forms of MTU is described now, for example, U.S. Pat-4710 at Om Ahuja, in 949, this device comprises a pair of voltage sensitive switch, one of them is configured in each end line and the loop wire, and another distinguishing terminal connects on the end line and loop wire on the user limit of this voltage sensitive switch, this voltage sensitive switch can each have about 16 volts threshold voltage, therefore under normal operating state, they are by 48 volts of cell voltage closures, still when being replaced by the test voltage that is lower than 32 volts, they will be opened, so that the impedance of p-wire-ground and end line-loop.This distinguishing terminal can for example comprise a back to back diode and Zener diode, when the big voltage (being higher than operating voltage) of opposed polarity is added to above them, will show asymmetric resistance.
Except that MTU is provided in communication system; this system generally need take safeguard measure to overload current in the communication channel and overload voltage, and for example these overload current voltages can be by equipment fault, electromagnetic interference; static discharge, it is caused to be connected to main power source etc.Usually contain just like gap in this system, triac isolated components such as (elements) can reach the protection purpose.
The present invention just is based on a kind of like this understanding; promptly might use same switching circuit to protect subscriber equipment or telephone office's (switch) equipment to avoid the curtage overload, these switching circuits are that user-isolated remotely actuated switch or loop restores test (Loop backtesting) and a device.
Therefore, the purpose of this invention is to provide a kind of switching device that can be connected in the communication channel.This switching device comprises that a pair of line is connected between the terminal equipment, and it comprises:
(i) switching circuit of pair of series, wherein each can be connected in series in the line, and when in its relation line current overload taking place, it will be opened, and/or
(ii) one or more branch switch circuit, they are connected between each line, perhaps are connected between a line-ground or two the line-ground, and when in the relation line betwixt voltage overload taking place, it is with closure;
Wherein, first switching circuit can be enough along passage by means of sending a stimulus remote operation;
It is characterized in that each tandem tap circuit comprises a switching transistor, the base stage of this pipe or grid voltage are controlled by a current overload control element, when this switching circuit met with current overload, this current overload control element was connected, and therefore this switching transistor was ended.
Have some advantages according to this switching device of the present invention; promptly in every signal line, adopt a signaling switch (for the situation of tandem tap) so that two functions to be provided; promptly remote the disconnection and overcurrent protection; improved the reliability of device thus; reduced its insertion loss in the line, and born the element amount and reduced its price, in addition owing to having reduced signal; shunt and tandem tap circuit can be operated arbitrarily, make the Distance Test circuit protection become possibility.
ON-OFF control circuit can be handled by any of some modes, for example the AC signal of a direct voltage on the available line or a given frequency.According to optimum device of the present invention, online connects a direct current voltage window detecting circuit (seeing a window detecting circuit here as), and and if only if when voltage between lines is in the preset range, to allow an electric current by it, will handle this switching circuit by the electric current of this window detecting circuit.
Owing in order to open the test voltage that tandem tap circuit and closed branch switch circuit are added to this device, usually during ring significantly less than the crest voltage that is applied, therefore, during that of this ringing cycle in the voltage that is applied is in this preset range, this switching circuit is attempted conversion.This conversion can comprise that in this device a low pass Lu ripple device with very low section this frequency is stoped by son.This desired cut-off frequency will depend on the width that rolls voltage range, and in this scope, electric current will flow in the window circuit; This scope is narrow more, and this cut-off frequency can be high more because each cycle time in preset range, the voltage that is applied will expend the less time, for example, the voltage range of 20V is with the cut-off frequency of corresponding about 300Hz.
The window detecting circuit of determining switch opens and the closed voltage that is applied can comprise a Zener diode, and it has set the voltage lower bound that causes that electric current flows and applied.The upper limit applies voltage and generally can be provided with easily by current overload switching circuit of son, and when electric current passes through this circuit, this circuit will be opened, and therefore, the voltage that puts on its two ends will be above a predetermined value.When in this scope of voltage place that is applied, the window circuit with a short signal to this switching circuit.
Has such advantage according to optimum device of the present invention, be that it can be handled by enough signals, this signal amplitude is between normal communication signal and bell signal, and do not need to trigger the bell signal of one or more switches, and need in this circuit, not use ring, shunt capacitance.The distortion of bell signal reduces as tandem tap by the operating overload current switching circuit.Can apply the such low voltage (0.6V) of a p-n junction pressure drop according to the circuit that adopts in apparatus of the present invention and just can be switched to conducting state, this situation will produce the cross distortion that is lower than 2V in conjunction with the voltage drop of any diode bridge of cross-over connection again in this bell signal.Under the situation that has the ring shunt capacitance, differ widely (about 32V voltage is by the voltage sensitive switch generation, and this switch application is in U.S. Pat-4710949) with the voltage of one of about 32V.
Tandem tap circuit solid switch normally in every circuit, generally make with silicon, and preferably include a switching transistor, its input voltage is controlled by a current overload control element, this element is connected when switching circuit suffers circuitous current overload, switching transistor is disconnected, and sort circuit itself will just switch according to current overload in its line related.Yet this circuit comprises a test control element, and it also controls the input voltage of this switching transistor.When electric current flow through the window circuit, this test control element was connected, and therefore, this switching transistor disconnects.So in this way, but this both remote operation of tandem tap circuit, and also the current overload in the available line is handled.Control element any number device is made, and control element be chosen in the model that depends on the switching transistor that is adopted in a way.This current overload control element for example can comprise a transistor, and its base stage or grid are fixed in the potential divider, this this switching transistor of voltage divider cross-over connection, so base-emitter or grid-source voltage increase with electric current in the circuit.This control element can comprise a comparator in addition, this comparator comprises cross-over connection, and this has the part voltage of the switching transistor of a reference voltage, and when this part voltage is opened this switch during greater than this reference voltage, as described in our (Copending) international application No PCT/GB91/02215 just on the docket.If a kind of general FET for example JFET or a kind of depletion type MOS FET as switching transistor, a negative voltage oscillator then, for example a kind of charge pump, or a kind of optical coupler (optocoupler) can be used as the control control element, as described in our Britain application No9114717 just on the docket.Disclosing these specifications here is to combine to use as reference.
Usually expectation can be independent of the operation of tandem tap circuit for the branch switch circuit.For example, during loop restores test (Loop backtest), this branch switch circuit needs closed so that determine the circuit continuity (in this case, the tandem tap circuit is to open or closure is not strict thing), and this branch switch circuit and this tandem tap circuit will all require to open, so that determine the insulation resistance (plug tip is to plug ring resistance or the like) of this circuit.For example, in order to handle different switches, can realize the independent operation of switch by changing the polarity of the direct current signal that is applied.For this situation, be used for can being connected to the signal input part of tandem tap circuit along separate routes the different circuit of window circuit, have only when the direct current control signal has correct polarity, wherein each electric current just is compelled to flow.
The time interval that each tandem tap circuit is preferably in after this manipulation direct current signal stops can be kept open mode, does not need to keep this direct current signal so that might carry out one or more tests on the line, perhaps as long as the polarity of this signal is inverted.For example, this circuit can stay open state and reach 1 minute, and more generally be to reach 20-40 second, and be at least usually for 5 seconds.In foregoing circuit, between test base-emitter end of control element or gate-to-source end, comprise-capacitor can realize.During handling this switching circuit with direct current signal, this capacitor is recharged, and keep this test control element conducting and therefore after this direct current signal is handled during in this switching transistor is ended.
The tandem tap circuit can use bipolar transistor and/or field-effect transistor, in the place of using pair transistor, preferably presses Darlington (darlington) structure as switching transistor, so that reduce desired base current when this transistor is connected.This base current must provide by a resistance that connects between this switching transistor base stage and collector electrode.When this circuit switches to its obstruction or during open mode, this switching transistor base current flows out by this control element (conducting now), and becomes leakage current.But because when this device was in cut-off state, the voltage drop at these resistance two ends was very high, therefore, this leakage current is greater than the base current of this switching transistor.If adopt a Darlington pair or three-way accumulation, then this effective DC current gain increases significantly, therefore can use very high resistance.
In the place that makes field-effect transistors, preferably use MOSFETS, for example can use enhancement mode MOSFET, though also available depletion type MOS FETS, particularly linear place is important.Depletion type MOS FET switch example above-mentioned we just on the docket UK Patent Application No91147173 in described.The resistance that is used in the switching circuit can provide with MOSFES, for example in the NMOS logic, couples together with their grid with drain electrode.In addition, this oxide-semiconductor control transistors be used for switching transistor base stage and grid and form the n-raceway groove of complementation of the FETs that the resistance of voltage divider can be connected by the CMOS logical course together and the p-raceway groove to providing.
Do not comprise preferably that for this tandem tap circuit resistance element connects with switching transistor, a kind of like this device will reduce voltage drop or go into loss along the skewer of circuit-line, in addition, reduce the silicon area of this device design required use in integrated circuit, reduced cost thus.
Usually the branch switch circuit will comprise the triac that is connected between line.The grid of this switch will be linked on the circuit by a pair of back-to-back Zener diode, and therefore an overvoltage bigger than this Zener breakdown voltage is applied to generation a current impulse of the grid of this reverse-blocking tetrode thyristor, and makes this reverse-blocking tetrode thyristor work.In addition, the grid of this reverse-blocking tetrode thyristor can be connected to the window circuit, and like this, the electric current that flows in this window circuit will also be handled this triac.As use the tandem tap circuit, in the branch switch circuit, will provide a low pass Lu ripple device, so that stop the beating of trouble of this shunt resistance with bell signal.This branch switch circuit can be together directly or by other element connection line.For example, these circuits can together couple together by a distinguishing terminal, and for example, by a diode and a back-to-back Zener diode, so the resistance of this terminal is non-linear, and polarity is interdependent.
This window circuit can be connected to this switching circuit by any-mode.For example, available body mode, they can connect by photoelectrical coupler.Body mode with other can be that this window circuit is arrived in direct-current coupling, for example, handles their voltage from the voltage drop at resistance two ends in the window circuit.
All elements of advantageous device are all got their power according to the electric current in the circuit or from the voltage drop between them, therefore do not need independent electric current main line.
Very possible situation is, some devices of production, its each have different direct current steering voltage windows, therefore, they can so that this passage is divided into plurality of sections, thereby be convenient to determine a fault along being connected on the difference of a long-channel.
Describe as an example by two kinds of devices of the present invention referring now to accompanying drawing:
Fig. 1 is the calcspar of expression according to apparatus of the present invention main element;
Fig. 2 is the circuit diagram of a kind of device form of representing among Fig. 1;
Fig. 3 is illustrated in device line voltage shown in Figure 2 and window circuit output voltage during the bell signal; And
Fig. 4 is the circuit diagram of second kind of form of device.
With reference to accompanying drawing, a kind of maintenance terminal unit 1 that is used for telephone line comprises a pair of interior tandem tap circuit 2 of every circuit that is arranged on a communication channel, and each tandem tap circuit is controlled by a window circuit 3.This window circuit 3 is also controlled an overload voltage dividing branch switching circuit 4, and it divides any overload voltage at current load two ends.In an alternating current circuit, an earth point may be provided, in this case, this voltage overload circuit can be used for overload voltage is diverted to ground.
For carrying out a kind of maintenance test on this circuit, this test can be customary or can be because certain user's complaint causes, produce will+80～100V direct voltage be added between line, so, these branch switch circuit 4 closed also collinear connecting together.This just makes a loop restore test and finishes, wherein energy measurement resistance completely.In case remove institute's making alive, this branch switch circuit will be opened.Apply-80～100V voltage between line, will cause tandem tap 2 to be opened, user and line will be isolated.After this voltage removes, the tandem tap circuit will stay open about 20 seconds time, and this can judge line-line and line-earth resistance.
Fig. 2 represents to form the electric circuit of MTU.
Each tandem tap circuit 2 and 2 ' comprise transistor T of three complementary darlington structures 1, T 2And T 3, at diode circuit BR 1Be connected in series in the interior relevant circuit, and constitute a switching transistor.The base terminal of the three-way accumulation of this Darlington is installed in by resistance R 1With overload current oxide-semiconductor control transistors T 4In the potential divider that constitutes, this voltage divider is crossed over the three-way accumulation of this Darlington, and this oxide-semiconductor control transistors T 4Base stage itself be installed in by resistance R 2And T 3In the potential divider that constitutes, it also crosses over the three-way accumulation switching transistor of this Darlington equally.Sort circuit is avoided overload current (as described below) in contact or the loop wire with protection system; when the voltage on the line when zero increases; the all crystals pipe will disconnect, and surpass pressure drop on the diode bridge up to the voltage at these circuit two ends and add that the single pn junction voltage that is used for switching transistor is reduced to and end.Switching transistor is conducting then, allowing current flowing, and oxide-semiconductor control transistors T 4Remain off.If the electric current in the line increases, then oxide-semiconductor control transistors T 4Base stage because R 3The voltage drop at two ends and will increasing, when suffering an overload current, transistor T 4Till the conducting.This will be directed at this switching transistor base-emitter short circuit, and this switching tube ends, and have blocking current to flow in the line thus.Under this state, leakage current will depend on R 1, R 2And R 3Value, they are generally in the scope of 50K Ω～1M Ω.100 П F capacitor C 1Same resistance R 3Be connected in parallel, to stop transistor T 1Conducting.This will prevent when this system connects for the first time, because the transient current of inductance and electric capacity causes beating of switching circuit on the line.In addition, Zener diode Z 1Connect transistor T 1Two ends are so that protect voltage that this switching circuit 2 avoids surpassing this transistor operating voltage for example, the big voltage that perceptual spiking causes.
Except current overload oxide-semiconductor control transistors T 4Outside, enhancement mode test control FETT 3Be connected between this switching transistor base stage and the emitter.FETT 5Gate terminal be connected to the window circuit, therefore, this switching circuit can switch on and off at a distance.
Branch switch circuit 4 comprises triac TR 1, it is connected between contact and the loop wire, and its gate terminal is by a pair of back-to-back Zener diode Z 5And Z 6And grid current limiting resistance R 17Be connected to end line.Be that an overvoltage surpasses Zener diode Z 5And Z 6Puncture voltage the time, a current impulse will be sent to this triac TR 1Grid, end line and loop wire short circuit as a result.An enhancement mode FETT 14Also be connected switch TR 1And between the end line, to allow switching branch switch circuit 4 at a distance.Diode D 5To FETT 14The reverse breakdown protection is provided.
The window circuit comprises a voltage level detector Zener diode Z 4With a current level testing circuit 6, their same diode bridge BR 2Be connected in series BR 2Itself be connected between end line and the loop wire and if only if Zener diode Z 4The voltage at two ends is 75V, when corresponding voltage between lines is 80V, and this Zener diode Z 4To allow electric current by this window circuit, and surpass to loop voltage on the electric current that 100V is associated with end line, current level testing circuit 6 will stop electric current and pass through this window circuit.Current level testing circuit 6 basically with tandem tap circuit 2 and 2 ' operation principle identical.Complementary darlington pair transistor T 7And T 8Constitute switching transistor, its base terminal will be contained in the resistance R by 1M Ω 11With oxide-semiconductor control transistors T 9In the potential divider that constitutes, and T 9Base terminal itself be installed in by a pair of 1M Ω resistance R 12And R 13In the voltage divider that constitutes.Work as T 7Both end voltage surpasses-and during the pressure drop of pn knot, electric current will circulate, up to R 13The voltage at two ends is high to making transistor T 9Till the conducting, so transistor T 8The base-emitter terminal shortcircuit, and this Darlington pair disconnects.
The input of three optical isolator OPTO1-3 is connected and voltage level detector Zener diode Z 4And current level testing circuit 6 and their output be in series, and their output is connected on series connection and the branch switch circuit.Isolator OPTO1 and OPTO2 are one another in series and are connected to a series of switching circuits, and with the OPTO3 optical isolator parallel connection that is connected to branch switch circuit 4.The input of optical isolator OPTO3 is connected with the opposite polarity of isolator OPTO1 and OPTO2, and therefore this series connection and branch switch circuit will be handled with the voltage that applies opposed polarity.Diode D 3And D 4Be the LEDS that is used for stoping in the optical isolator, cause reverse breakdown owing to having applied a big reverse voltage.
Have direct current signal between the 80-100V of correct polarity when being applied to this circuit when one, about 10mA electric current will be by the LED input of optical isolator OPTO1 and OPTO2.The input of each optical isolator passes through by resistance R 5And capacitor C 3A low pass RC Lu ripple device that constitutes, this capacitor C 3To stop the parasitism of switching circuit to trigger, and to being connected test control FETT 5Grid-source electrode between capacitor C 2Charging.Diode D 1Allowing electric current to flow into this capacitor from OPTO1, is unallowed but change direction mobile, therefore, and capacitor C 1Discharge also be by being connected FETT 5Grid-source electrode between resistance R 4Control.
Like this, in case capacitor C 2Enough be charged to and surpass test control FETT 5Grid voltage, the tandem tap circuit is opened, thereby disconnects with the user, and will keep after removing the manipulation direct current signal and open, up to capacitor C 2Passed through resistance R 4Till the discharge.
The LED of optical isolator OPTO3 if the pole reversal of the direct current signal that applies, a 10mA electric current will circulate, this output voltage passes through by resistance R 14, R 15, R 16, C 7And C 8A low pass RC Lu ripple device that constitutes is added to FETT 14Grid, this will make the FET conducting and control triac and make two line short circuits effectively, allow the loop of system to restore test simultaneously.
This device even can to use in fault be because the occasion of subscriber equipment short circuit.In this case, all reduce to along the line, therefore, desired steering voltage can not be applied to this window circuit at any voltage that switch applies.But if the voltage that is applied drops to low 3.6V, then switch closure can not be fully kept in the voltage drop that causes of the switching transistor two ends of each tandem tap, and fault can be localized like this.
As shown in Figure 3, because bell signal on line can stop along separate routes and the triggering of the parasitism of tandem tap circuit, Fig. 3 a represents when a bell signal is transmitted, the voltage that occurs on end line and loop wire.This signal comprise be superimposed upon-on the 48V cell voltage, frequency is that the RMS amplitude of 20Hz is a sinusoidal bell signal of 80V (peak-peak is 226V).Though the instantaneous voltage on the line surpasses test voltage for time interval of putting shake, in the bell signal forward position, when the voltage on the line between 80 and 100V between the time, in window circuit 3, just produce transient current.Fig. 3 b represents the input (line 1) to optical isolator.It is made up of the wide pulse train of about 1.7ms and occurs in each ringing cycle.Be expressed as line 2 from the output (opening end) of optical isolator.When the LED electric current rose to about 5mA, this output began to rise.This pulse train easily in the tandem tap circuit by means of by C 3And R 5The RC Lu ripple device that constitutes and in the branch switch circuit by means of by C 7, C 8, R 14, R 15And R 16In addition filtering of the Lu ripple device that constitutes.Usually these Lu ripple devices will have the cut-off point of 50Hz at least, but be not more than 500Hz.
Fig. 4 represents another kind of device mode, and wherein the window circuit is directly coupled to the tandem tap circuit.Tandem tap circuit 2 and 2 ' be shown in Figure 2 roughly the same, and in conjunction with current level testing circuit 6 and Zener diode Z 4, be used for determining the voltage window of master cock.
Tandem tap circuit 2 comprises a P-channel enhancement type FET41 and switching circuit 2 ' comprises that a n-channel enhancement FET42 is as the test control element.
The window circuit comprises a pair of resistance 44 and 47 that FETs41 and 42 grid voltages are provided.Capacitor 9 and 10 is with resistance 44 and 47 parallel connections, so that the parasitic signal of any weak point is removed in the Lu, and therefore in case receive correct test voltage and will charge immediately, and after the direct current control signal stops, will make FETs41 and 42 stay open a period of time.The control diode is to be used to provide the reverse system voltage that prevents to influence these two FETs41 and 42.
When receiving a test voltage signal, the electric current window circuit 3 that will circulate, and will improve the voltage at resistance 44 and 47 two ends, when more being defeated by its source electrode for the grid of taking FET41, simultaneously the grid of FET42 is corrected when its source electrode, the result will open switching circuit 2 and 2 '.
A similarly auxiliary reversed polarity window circuit also can provide and control a branch switch circuit.

Claims (9)

1. the switching device that can be connected in the communication channel comprises a pair of line, terminal equipment therebetween, and this equipment comprises:
(i) pair of series switching circuit, wherein each can be connected in series in the line, and when in relative circuit, meeting with current overload, open with and/or
(ii) one or more be connected between this line or be connected between one line-ground, or be connected branch switch circuit between two lines-ground, and when in relative circuit, meeting with voltage overload closure
Wherein, each switching circuit can be used a test signal remote operation along this channel transfer;
It is characterized in that each tandem tap circuit comprises a switching transistor, this transistorized base stage or grid voltage are controlled by a current overload control element, when this switching circuit met with current overload, this current overload control element was connected, and therefore this switching transistor was ended.
2. press a kind of switching device of claim 1, it is characterized in that this current overload control element is a transistor, its base stage or gate terminal are installed in the potentiometer that binds the tandem tap circuit, therefore, its base-emitter or grid-source voltage increase with the electric current in the circuit.
3. by a kind of switching device of claim 1, it is characterized in that each tandem tap circuit comprises a test control element, this control element is also controlled the base stage or the grid voltage of this switching transistor, and in response to this test signal, this test control element is connected.
4. press a kind of switching device of claim 1, it is characterized in that, comprise connecting a direct current voltage window detector circuit of online that and if only if voltage between lines will allow electric current to flow through it when being in a preset range, the electric current that flows through the window detector circuit is handled this switching circuit.
5. by a kind of switching device of claim 1, it is characterized in that when being handled by test signal, the branch switch circuit is by the special-purpose terminal connection line.
6. by a kind of switching device of claim 1, it is characterized in that the branch switch circuit comprises the three-way bi-directional thyristor switch of online of connection.
7. by a kind of switching device of claim 4, it is characterized in that the window detector circuit is coupled on this switching circuit by a photoelectrical coupler.
8. press a kind of switching device of claim 1, it is characterized in that, each tandem tap circuit comprises the capacitor that is connected to an input of test oxide-semiconductor control transistors, this capacitor charges during handling this switching circuit with direct current signal, and during stopping handling direct current signal this switching circuit is stayed open.
9. press a kind of switching device array of the arbitrary claim of claim 1-8, it is characterized in that being connected in the communication channel, so that this passage is divided into plurality of sections, to be used for determining fault, each device has a different direct voltage and handles window, and this window is from this device or device to each other.
CN93109522A 1992-07-01 1993-07-01 Remotely actuated switch and protection circuit Expired - Fee Related CN1076920C (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB929213992A GB9213992D0 (en) 1992-07-01 1992-07-01 Remotely actuated switch and protection circuit
GB9213992.2 1992-07-01

Publications (2)

Publication Number Publication Date
CN1085701A CN1085701A (en) 1994-04-20
CN1076920C true CN1076920C (en) 2001-12-26

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CN93109522A Expired - Fee Related CN1076920C (en) 1992-07-01 1993-07-01 Remotely actuated switch and protection circuit

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US (1) US5604785A (en)
EP (1) EP0649584B1 (en)
JP (1) JPH07508624A (en)
CN (1) CN1076920C (en)
AT (1) ATE170029T1 (en)
AU (1) AU681587B2 (en)
BG (1) BG99314A (en)
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SK160894A3 (en) 1995-09-13
MY113346A (en) 2002-01-31
HU9403806D0 (en) 1995-02-28
CN1085701A (en) 1994-04-20
CZ334894A3 (en) 1995-08-16
NO945081D0 (en) 1994-12-29
WO1994001960A1 (en) 1994-01-20
CA2139435A1 (en) 1994-01-20
GB9213992D0 (en) 1992-08-12
AU4507293A (en) 1994-01-31
BR9306640A (en) 1998-12-08
US5604785A (en) 1997-02-18
HUT73888A (en) 1996-10-28
IL106194A (en) 1996-10-16
DE69320479D1 (en) 1998-09-24
TW232107B (en) 1994-10-11
EP0649584A1 (en) 1995-04-26
AU681587B2 (en) 1997-09-04
DE69320479T2 (en) 1999-04-29
NZ253746A (en) 1996-05-28
BG99314A (en) 1995-10-31
ATE170029T1 (en) 1998-09-15
ES2120507T3 (en) 1998-11-01
IL106194A0 (en) 1993-10-20
NO945081L (en) 1994-12-29
FI946187A0 (en) 1994-12-30
EP0649584B1 (en) 1998-08-19
FI110906B (en) 2003-04-15
FI946187A (en) 1994-12-30
JPH07508624A (en) 1995-09-21

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